There is an extensive body of literature on the purification of organic compounds especially in the practice of the removal of water from organic liquids. See, e.g., Williams et al., J. Org. Chem. 75:8351-4 (2010); Maslan et al., J. Phys. Chem. 60(8):1146-7 (1956). Conventional processes include distillation, use of dehydrating agents, and recrystallization, which are used alone or in combination. However, distillation is ineffective for organic liquids that form lower boiling azeotropes. Azeotropic distillation results in the formation of byproducts that are used to break the azeotrope. For example, benzene and toluene are used for the azeotropic distillation of ethanol resulting in hazardous waste mixtures of benzene/water and toluene/water requiring further treatment. Dehydrating agents such as alumina, magnesium sulfate, molecular sieves and sodium sulfate are also established methods for removal of water from organic liquids and from solutions of solutes in organic solvents.
For example, acetonitrile is a polar solvent with a high dielectric constant that has a strong affinity for polar compounds, such as organometallic complexes, metal chelates, ion pairs and organic solutes. Acetonitrile is miscible with water in all proportions. Acetonitrile is an excellent organic solvent and has become widely used in organic synthesis and manufacturing, as well as for purity and quality control analysis of organic compounds used in pharmaceuticals, cosmetics, personal care products and many other applications in research and development. In the latter aspects, the miscibility of acetonitrile in water renders it one of the most useful solvents for reverse phase high pressure liquid chromatography (RP-HPLC). Several events have resulted in a shortage in acetonitrile causing prices of this solvent to rise dramatically. See, e.g., Majors, et al., LC-GC North America 27:458-71 (2009); McConvey et al., Org. Proc. Res. Dev. 16:612-24 (2012); and Venkatasami, Sowa, Anal. Chim. Acta 665:227-30 (2010). Thus, there is unprecedented interest in the recovery of acetonitrile from research and manufacturing and RP-HPLC waste streams. However, like many other organic solvents, acetonitrile forms an azeotrope with water, which as persons skilled in the art appreciate, is a liquid mixture the individual components of which cannot be separated from each other by distillation. According to the literature, since the azeotrope boils at 76° C. and is composed of 86% acetonitrile and 14% water, there is no possibility of obtaining acetonitrile of purity above 86% by distillation and more costly processes are required to purify acetonitrile to a level higher than the azeotrope.
U.S. Patent Application Publication 2009/0090894, to Wang et al., teaches a method for separating acetonitrile from water that utilizes a saccharide (monosaccharide or disaccharide), and that the acetonitrile in the so-called “sugared-out” upper phase can reach a purity of 95.4%.
Notwithstanding a greater need for recycling, concern persists that unimpeded use of our natural resources is wasting essential resources and contributing toward global warming which if unchecked, will dramatically impact daily life. Emergent initiatives known as “sustainable manufacturing”, “sustainability”, “green manufacturing”, “green technology” and “green chemistry” are designed to encourage better and more economical use of natural resources and to minimize any negative impact on the environment. They also aim towards making manufacturing process more economical, reducing costs of disposal through recycling and providing “green” products. In the area of chemical manufacturing there is a great need to improve research and manufacturing processes by developing new sustainable, green chemical processes (Anastas, Warner “Green Chemistry Theory and Practice”, Oxford, 2000).